[MxxCon]

ok, let's start over.
there is no internet connection sharing feature in win98, it's only in winxp.

start from the simplest config
connect your pc directly to your xbox without any hubs or routers or modems.
try transfering files.
if you still get slow speed then it's something on your system,
if speed is normal, add your hub/router(btw, which one is it? in some posts you say hub, in other you say router? they are very different things so you need to be specific).
if after connecting it your speeds slow down then it's something to do with your hub/router. otherwise keep connecting additional devices untill you restore your previous config.